No suppression of sidebands TRX2

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No suppression of sidebands TRX2

Postby ZL2LDX » 01 Aug 2016 00:39

Hello

This is my first post to the group. I am building a TRX2 for a friend and all was well until testing of the receiver. I found that a LSB signal was being received on USB just as well as it was on LSB!! After much checking of circuit diagram and inspection of my soldering, nothing seemed to make any difference. I even swapped the polyphase boards and the fault persisted - no change. To cut a long story short, discussion with other radio operators about the problem suggested a second look at the polyphase boards. Found it - several dry joints which were corrected and all was well. Transmit performance also improved. Everyone is now happy. Now building the 100W PA(D)

Cheers.

Don
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Re: No suppression of sidebands TRX2

Postby OH7SV » 08 Aug 2016 19:31

Don,

Good to hear that you found the problem :)

Those 'dry' solderings are qute very typical. I recommend to use more time during soldering. The components can stand lot of heat.

Ps. You can fine tune the opposite side band attenuation with the I/Q trimmer R42 on DDS board
http://www.jumaradio.com/juma-trx2/rev- ... -B-sch.pdf

73 Matti OH7SV
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